How to prevent caching of php files?

Question

After removing varnish cache from local server I noticed strange behaviour of Apache server. When ever you update a php file and try to open it in a browser old response is shown, CTRL + F5 does not refresh a page, but if you type in service apache2 restart all changes appear.

Can some one point what could possibly went wrong?

Solution

You may have apc.stat set to 0 in which case APC will always serve the cached version of PHP files without checking the file on disk for changes anymore.

You can find out with a <?php phpinfo() ?> on any page.

To change that setting, check the content of /etc/php5/conf.d/apc.ini.